osfmk/kern/ast.c

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * @OSF_COPYRIGHT@
  24  */
  25 /*
  26  * Mach Operating System
  27  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  28  * All Rights Reserved.
  29  *
  30  * Permission to use, copy, modify and distribute this software and its
  31  * documentation is hereby granted, provided that both the copyright
  32  * notice and this permission notice appear in all copies of the
  33  * software, derivative works or modified versions, and any portions
  34  * thereof, and that both notices appear in supporting documentation.
  35  *
  36  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  37  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  38  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  39  *
  40  * Carnegie Mellon requests users of this software to return to
  41  *
  42  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  43  *  School of Computer Science
  44  *  Carnegie Mellon University
  45  *  Pittsburgh PA 15213-3890
  46  *
  47  * any improvements or extensions that they make and grant Carnegie Mellon
  48  * the rights to redistribute these changes.
  49  */
  50 /*
  51  */
  52
  53 /*
  54  *
  55  *      This file contains routines to check whether an ast is needed.
  56  *
  57  *      ast_check() - check whether ast is needed for interrupt or context
  58  *      switch.  Usually called by clock interrupt handler.
  59  *
  60  */
  61
  62 #include <cputypes.h>
  63 #include <platforms.h>
  64
  65 #include <kern/ast.h>
  66 #include <kern/counters.h>
  67 #include <kern/cpu_number.h>
  68 #include <kern/misc_protos.h>
  69 #include <kern/queue.h>
  70 #include <kern/sched_prim.h>
  71 #include <kern/thread.h>
  72 #include <kern/processor.h>
  73 #include <kern/spl.h>
  74 #include <kern/wait_queue.h>
  75 #include <mach/policy.h>
  76
  77 #ifdef __ppc__
  78 #include <ppc/trap.h> // for CHUD AST hook
  79 #endif
  80
  81 void
  82 ast_init(void)
  83 {
  84 }
  85
  86 /*
  87  * Called at splsched.
  88  */
  89 void
  90 ast_taken(
  91         ast_t           reasons,
  92         boolean_t       enable
  93 )
  94 {
  95         boolean_t               preempt_trap = (reasons == AST_PREEMPTION);
  96         ast_t                   *myast = ast_pending();
  97         thread_t                thread = current_thread();
  98
  99 #ifdef __ppc__
 100         /*
 101          * CHUD hook - all threads including idle processor threads
 102          */
 103         if(perfASTHook) {
 104                 if(*myast & AST_PPC_CHUD_ALL) {
 105                         perfASTHook(0, NULL, 0, 0);
 106
 107                         if(*myast == AST_NONE) {
 108                                 return; // nothing left to do
 109                         }
 110                 }
 111         } else {
 112                 *myast &= ~AST_PPC_CHUD_ALL;
 113         }
 114 #endif
 115
 116         reasons &= *myast;
 117         *myast &= ~reasons;
 118
 119         /*
 120          * Handle ASTs for all threads
 121          * except idle processor threads.
 122          */
 123         if (!(thread->state & TH_IDLE)) {
 124                 /*
 125                  * Check for urgent preemption.
 126                  */
 127                 if (    (reasons & AST_URGENT)                          &&
 128                                 wait_queue_assert_possible(thread)              ) {
 129                         if (reasons & AST_PREEMPT) {
 130                                 counter(c_ast_taken_block++);
 131                                 thread_block_reason(THREAD_CONTINUE_NULL, NULL,
 132                                                                                 AST_PREEMPT | AST_URGENT);
 133                         }
 134
 135                         reasons &= ~AST_PREEMPTION;
 136                 }
 137
 138                 /*
 139                  * The kernel preempt traps
 140                  * skip all other ASTs.
 141                  */
 142                 if (!preempt_trap) {
 143                         ml_set_interrupts_enabled(enable);
 144
 145 #ifdef  MACH_BSD
 146                         /*
 147                          * Handle BSD hook.
 148                          */
 149                         if (reasons & AST_BSD) {
 150                                 thread_ast_clear(thread, AST_BSD);
 151                                 bsd_ast(thread);
 152                         }
 153 #endif
 154
 155                         /*
 156                          * Thread APC hook.
 157                          */
 158                         if (reasons & AST_APC)
 159                                 act_execute_returnhandlers();
 160
 161                         ml_set_interrupts_enabled(FALSE);
 162
 163                         /*
 164                          * Check for preemption.
 165                          */
 166                         if (reasons & AST_PREEMPT) {
 167                                 processor_t             myprocessor = current_processor();
 168
 169                                 if (csw_needed(thread, myprocessor))
 170                                         reasons = AST_PREEMPT;
 171                                 else
 172                                         reasons = AST_NONE;
 173                         }
 174                         if (    (reasons & AST_PREEMPT)                         &&
 175                                         wait_queue_assert_possible(thread)              ) {
 176                                 counter(c_ast_taken_block++);
 177                                 thread_block_reason((thread_continue_t)thread_exception_return, NULL, AST_PREEMPT);
 178                         }
 179                 }
 180         }
 181
 182         ml_set_interrupts_enabled(enable);
 183 }
 184
 185 /*
 186  * Called at splsched.
 187  */
 188 void
 189 ast_check(
 190         processor_t             processor)
 191 {
 192         register thread_t               thread = processor->active_thread;
 193
 194         processor->current_pri = thread->sched_pri;
 195         if (    processor->state == PROCESSOR_RUNNING           ||
 196                         processor->state == PROCESSOR_SHUTDOWN          ) {
 197                 register ast_t          preempt;
 198
 199                 /*
 200                  *      Propagate thread ast to processor.
 201                  */
 202                 ast_propagate(thread->ast);
 203
 204                 /*
 205                  *      Context switch check.
 206                  */
 207                 if ((preempt = csw_check(thread, processor)) != AST_NONE)
 208                         ast_on(preempt);
 209         }
 210 }